The present invention relates generally to acoustic homing torpedoes and more specifically to the reduction of torpedo self-noise therefrom.
Acoustic homing torpedoes are generally constructed with an acoustic transducer section at the forward end of the torpedo nose shell. The transducer section contains transducer elements mounted behind an acoustically transparent dome which forms the nose end of the torpedo. The sensitive transducer elements presently in use are responsive not only to target noise, but also to the self-noise generated by the torpedo as it moves through the water. One source of the self-noise is the turbulence caused by the discontinuity at the joint where the transducer dome is affixed to the torpedo nose shell, resulting from the difficulty in machining the parts to achieve a perfectly smooth transition. This is particularly a problem when the torpedo is operating at shallow depths, since any discontinuities on the torpedo shell contribute to cavitation.
One method used in the prior art to overcome this problem was to machine the transducer to nose shell joint to a smooth contour, after the torpedo had been assembled. While this provided acceptable hydrodynamic performance, the assembly had to be re-machined after the torpedo was repaired or refurbished to again achieve a smooth contour. Another method involved redesigning of the nose section to include on the transducer dome a skirt that extended rearward of the normal dome-nose section interface. This had the effect of shifting the noise source to a position where it would have a reduced effect on the performance of the torpedo. This method involves considerable time and expense, however, in that it necessitates the scrapping of existing nose sections and the installation of new ones on all torpedoes for which improved performance is required.
Thus, there is a need for an effective torpedo self-noise reduction device that is less costly and easier to install than prior art devices.